xref: /freebsd/contrib/llvm-project/llvm/lib/Target/NVPTX/NVPTXAsmPrinter.h (revision 6966ac055c3b7a39266fb982493330df7a097997)
1 //===-- NVPTXAsmPrinter.h - NVPTX LLVM assembly writer ----------*- C++ -*-===//
2 //
3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4 // See https://llvm.org/LICENSE.txt for license information.
5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6 //
7 //===----------------------------------------------------------------------===//
8 //
9 // This file contains a printer that converts from our internal representation
10 // of machine-dependent LLVM code to NVPTX assembly language.
11 //
12 //===----------------------------------------------------------------------===//
13 
14 #ifndef LLVM_LIB_TARGET_NVPTX_NVPTXASMPRINTER_H
15 #define LLVM_LIB_TARGET_NVPTX_NVPTXASMPRINTER_H
16 
17 #include "NVPTX.h"
18 #include "NVPTXSubtarget.h"
19 #include "NVPTXTargetMachine.h"
20 #include "llvm/ADT/DenseMap.h"
21 #include "llvm/ADT/SmallVector.h"
22 #include "llvm/ADT/StringRef.h"
23 #include "llvm/CodeGen/AsmPrinter.h"
24 #include "llvm/CodeGen/MachineFunction.h"
25 #include "llvm/CodeGen/MachineLoopInfo.h"
26 #include "llvm/IR/Constants.h"
27 #include "llvm/IR/DebugLoc.h"
28 #include "llvm/IR/DerivedTypes.h"
29 #include "llvm/IR/Function.h"
30 #include "llvm/IR/GlobalValue.h"
31 #include "llvm/IR/Value.h"
32 #include "llvm/MC/MCExpr.h"
33 #include "llvm/MC/MCStreamer.h"
34 #include "llvm/MC/MCSymbol.h"
35 #include "llvm/PassAnalysisSupport.h"
36 #include "llvm/Support/Casting.h"
37 #include "llvm/Support/Compiler.h"
38 #include "llvm/Support/ErrorHandling.h"
39 #include "llvm/Support/raw_ostream.h"
40 #include "llvm/Target/TargetMachine.h"
41 #include <algorithm>
42 #include <cassert>
43 #include <map>
44 #include <memory>
45 #include <string>
46 #include <vector>
47 
48 // The ptx syntax and format is very different from that usually seem in a .s
49 // file,
50 // therefore we are not able to use the MCAsmStreamer interface here.
51 //
52 // We are handcrafting the output method here.
53 //
54 // A better approach is to clone the MCAsmStreamer to a MCPTXAsmStreamer
55 // (subclass of MCStreamer).
56 
57 namespace llvm {
58 
59 class MCOperand;
60 
61 class LLVM_LIBRARY_VISIBILITY NVPTXAsmPrinter : public AsmPrinter {
62 
63   class AggBuffer {
64     // Used to buffer the emitted string for initializing global
65     // aggregates.
66     //
67     // Normally an aggregate (array, vector or structure) is emitted
68     // as a u8[]. However, if one element/field of the aggregate
69     // is a non-NULL address, then the aggregate is emitted as u32[]
70     // or u64[].
71     //
72     // We first layout the aggregate in 'buffer' in bytes, except for
73     // those symbol addresses. For the i-th symbol address in the
74     //aggregate, its corresponding 4-byte or 8-byte elements in 'buffer'
75     // are filled with 0s. symbolPosInBuffer[i-1] records its position
76     // in 'buffer', and Symbols[i-1] records the Value*.
77     //
78     // Once we have this AggBuffer setup, we can choose how to print
79     // it out.
80   public:
81     unsigned numSymbols;   // number of symbol addresses
82 
83   private:
84     const unsigned size;   // size of the buffer in bytes
85     std::vector<unsigned char> buffer; // the buffer
86     SmallVector<unsigned, 4> symbolPosInBuffer;
87     SmallVector<const Value *, 4> Symbols;
88     // SymbolsBeforeStripping[i] is the original form of Symbols[i] before
89     // stripping pointer casts, i.e.,
90     // Symbols[i] == SymbolsBeforeStripping[i]->stripPointerCasts().
91     //
92     // We need to keep these values because AggBuffer::print decides whether to
93     // emit a "generic()" cast for Symbols[i] depending on the address space of
94     // SymbolsBeforeStripping[i].
95     SmallVector<const Value *, 4> SymbolsBeforeStripping;
96     unsigned curpos;
97     raw_ostream &O;
98     NVPTXAsmPrinter &AP;
99     bool EmitGeneric;
100 
101   public:
102     AggBuffer(unsigned size, raw_ostream &O, NVPTXAsmPrinter &AP)
103         : size(size), buffer(size), O(O), AP(AP) {
104       curpos = 0;
105       numSymbols = 0;
106       EmitGeneric = AP.EmitGeneric;
107     }
108 
109     unsigned addBytes(unsigned char *Ptr, int Num, int Bytes) {
110       assert((curpos + Num) <= size);
111       assert((curpos + Bytes) <= size);
112       for (int i = 0; i < Num; ++i) {
113         buffer[curpos] = Ptr[i];
114         curpos++;
115       }
116       for (int i = Num; i < Bytes; ++i) {
117         buffer[curpos] = 0;
118         curpos++;
119       }
120       return curpos;
121     }
122 
123     unsigned addZeros(int Num) {
124       assert((curpos + Num) <= size);
125       for (int i = 0; i < Num; ++i) {
126         buffer[curpos] = 0;
127         curpos++;
128       }
129       return curpos;
130     }
131 
132     void addSymbol(const Value *GVar, const Value *GVarBeforeStripping) {
133       symbolPosInBuffer.push_back(curpos);
134       Symbols.push_back(GVar);
135       SymbolsBeforeStripping.push_back(GVarBeforeStripping);
136       numSymbols++;
137     }
138 
139     void print() {
140       if (numSymbols == 0) {
141         // print out in bytes
142         for (unsigned i = 0; i < size; i++) {
143           if (i)
144             O << ", ";
145           O << (unsigned int) buffer[i];
146         }
147       } else {
148         // print out in 4-bytes or 8-bytes
149         unsigned int pos = 0;
150         unsigned int nSym = 0;
151         unsigned int nextSymbolPos = symbolPosInBuffer[nSym];
152         unsigned int nBytes = 4;
153         if (static_cast<const NVPTXTargetMachine &>(AP.TM).is64Bit())
154           nBytes = 8;
155         for (pos = 0; pos < size; pos += nBytes) {
156           if (pos)
157             O << ", ";
158           if (pos == nextSymbolPos) {
159             const Value *v = Symbols[nSym];
160             const Value *v0 = SymbolsBeforeStripping[nSym];
161             if (const GlobalValue *GVar = dyn_cast<GlobalValue>(v)) {
162               MCSymbol *Name = AP.getSymbol(GVar);
163               PointerType *PTy = dyn_cast<PointerType>(v0->getType());
164               bool IsNonGenericPointer = false; // Is v0 a non-generic pointer?
165               if (PTy && PTy->getAddressSpace() != 0) {
166                 IsNonGenericPointer = true;
167               }
168               if (EmitGeneric && !isa<Function>(v) && !IsNonGenericPointer) {
169                 O << "generic(";
170                 Name->print(O, AP.MAI);
171                 O << ")";
172               } else {
173                 Name->print(O, AP.MAI);
174               }
175             } else if (const ConstantExpr *CExpr = dyn_cast<ConstantExpr>(v0)) {
176               const MCExpr *Expr =
177                 AP.lowerConstantForGV(cast<Constant>(CExpr), false);
178               AP.printMCExpr(*Expr, O);
179             } else
180               llvm_unreachable("symbol type unknown");
181             nSym++;
182             if (nSym >= numSymbols)
183               nextSymbolPos = size + 1;
184             else
185               nextSymbolPos = symbolPosInBuffer[nSym];
186           } else if (nBytes == 4)
187             O << *(unsigned int *)(&buffer[pos]);
188           else
189             O << *(unsigned long long *)(&buffer[pos]);
190         }
191       }
192     }
193   };
194 
195   friend class AggBuffer;
196 
197 private:
198   StringRef getPassName() const override { return "NVPTX Assembly Printer"; }
199 
200   const Function *F;
201   std::string CurrentFnName;
202 
203   void EmitBasicBlockStart(const MachineBasicBlock &MBB) const override;
204   void EmitFunctionEntryLabel() override;
205   void EmitFunctionBodyStart() override;
206   void EmitFunctionBodyEnd() override;
207   void emitImplicitDef(const MachineInstr *MI) const override;
208 
209   void EmitInstruction(const MachineInstr *) override;
210   void lowerToMCInst(const MachineInstr *MI, MCInst &OutMI);
211   bool lowerOperand(const MachineOperand &MO, MCOperand &MCOp);
212   MCOperand GetSymbolRef(const MCSymbol *Symbol);
213   unsigned encodeVirtualRegister(unsigned Reg);
214 
215   void printMemOperand(const MachineInstr *MI, int opNum, raw_ostream &O,
216                        const char *Modifier = nullptr);
217   void printModuleLevelGV(const GlobalVariable *GVar, raw_ostream &O,
218                           bool = false);
219   void printParamName(Function::const_arg_iterator I, int paramIndex,
220                       raw_ostream &O);
221   void emitGlobals(const Module &M);
222   void emitHeader(Module &M, raw_ostream &O, const NVPTXSubtarget &STI);
223   void emitKernelFunctionDirectives(const Function &F, raw_ostream &O) const;
224   void emitVirtualRegister(unsigned int vr, raw_ostream &);
225   void emitFunctionParamList(const Function *, raw_ostream &O);
226   void emitFunctionParamList(const MachineFunction &MF, raw_ostream &O);
227   void setAndEmitFunctionVirtualRegisters(const MachineFunction &MF);
228   void printReturnValStr(const Function *, raw_ostream &O);
229   void printReturnValStr(const MachineFunction &MF, raw_ostream &O);
230   bool PrintAsmOperand(const MachineInstr *MI, unsigned OpNo,
231                        const char *ExtraCode, raw_ostream &) override;
232   void printOperand(const MachineInstr *MI, int opNum, raw_ostream &O);
233   bool PrintAsmMemoryOperand(const MachineInstr *MI, unsigned OpNo,
234                              const char *ExtraCode, raw_ostream &) override;
235 
236   const MCExpr *lowerConstantForGV(const Constant *CV, bool ProcessingGeneric);
237   void printMCExpr(const MCExpr &Expr, raw_ostream &OS);
238 
239 protected:
240   bool doInitialization(Module &M) override;
241   bool doFinalization(Module &M) override;
242 
243 private:
244   bool GlobalsEmitted;
245 
246   // This is specific per MachineFunction.
247   const MachineRegisterInfo *MRI;
248   // The contents are specific for each
249   // MachineFunction. But the size of the
250   // array is not.
251   typedef DenseMap<unsigned, unsigned> VRegMap;
252   typedef DenseMap<const TargetRegisterClass *, VRegMap> VRegRCMap;
253   VRegRCMap VRegMapping;
254 
255   // List of variables demoted to a function scope.
256   std::map<const Function *, std::vector<const GlobalVariable *>> localDecls;
257 
258   void emitPTXGlobalVariable(const GlobalVariable *GVar, raw_ostream &O);
259   void emitPTXAddressSpace(unsigned int AddressSpace, raw_ostream &O) const;
260   std::string getPTXFundamentalTypeStr(Type *Ty, bool = true) const;
261   void printScalarConstant(const Constant *CPV, raw_ostream &O);
262   void printFPConstant(const ConstantFP *Fp, raw_ostream &O);
263   void bufferLEByte(const Constant *CPV, int Bytes, AggBuffer *aggBuffer);
264   void bufferAggregateConstant(const Constant *CV, AggBuffer *aggBuffer);
265 
266   void emitLinkageDirective(const GlobalValue *V, raw_ostream &O);
267   void emitDeclarations(const Module &, raw_ostream &O);
268   void emitDeclaration(const Function *, raw_ostream &O);
269   void emitDemotedVars(const Function *, raw_ostream &);
270 
271   bool lowerImageHandleOperand(const MachineInstr *MI, unsigned OpNo,
272                                MCOperand &MCOp);
273   void lowerImageHandleSymbol(unsigned Index, MCOperand &MCOp);
274 
275   bool isLoopHeaderOfNoUnroll(const MachineBasicBlock &MBB) const;
276 
277   // Used to control the need to emit .generic() in the initializer of
278   // module scope variables.
279   // Although ptx supports the hybrid mode like the following,
280   //    .global .u32 a;
281   //    .global .u32 b;
282   //    .global .u32 addr[] = {a, generic(b)}
283   // we have difficulty representing the difference in the NVVM IR.
284   //
285   // Since the address value should always be generic in CUDA C and always
286   // be specific in OpenCL, we use this simple control here.
287   //
288   bool EmitGeneric;
289 
290 public:
291   NVPTXAsmPrinter(TargetMachine &TM, std::unique_ptr<MCStreamer> Streamer)
292       : AsmPrinter(TM, std::move(Streamer)),
293         EmitGeneric(static_cast<NVPTXTargetMachine &>(TM).getDrvInterface() ==
294                     NVPTX::CUDA) {}
295 
296   bool runOnMachineFunction(MachineFunction &F) override;
297 
298   void getAnalysisUsage(AnalysisUsage &AU) const override {
299     AU.addRequired<MachineLoopInfo>();
300     AsmPrinter::getAnalysisUsage(AU);
301   }
302 
303   std::string getVirtualRegisterName(unsigned) const;
304 
305   const MCSymbol *getFunctionFrameSymbol() const override;
306 };
307 
308 } // end namespace llvm
309 
310 #endif // LLVM_LIB_TARGET_NVPTX_NVPTXASMPRINTER_H
311